Conservation Framing

Conservation Framing of Works of Art on Paper

Paper is sensitive to its surroundings: it can be adversely affected by damp conditions, changes in temperature and humidity, restriction of movement, and exposure to light. Paper will also react to the materials with which it is in contact such as acidic support boards and self adhesive tapes. Evidence of damage caused by adverse conditions can be seen in pictures with mat burns, foxing (small brown spots), fading of pigments or darkening, and increasing brittleness of the paper.

Preparing a Picture for Framing

If the picture is damaged, foxed, stained or stuck down on an acid based backing (card board, ply wood, old mat board-pre-1983), a paper conservator can advise on preservation and conservation options. In some cases, preservation may mean leaving it alone and simply ensuring that the picture is well protected through conservation framing. In other cases conservation treatment may be essential to protect the picture long-term.

Never trim or fold the picture to fit a frame.

Never flatten the print by dry-mounting or gluing it down to any sort of backing board.

Never use self adhesive tapes to repair a picture or document: ie Scotch®-tape or masking tape.

The Frame

The framing of a work of art may involve making a choice between re-using an existing frame and selecting a new one.
The rabbet should be deep enough to hold the glass, mat or mats, piece of art, under mount, and back board.

Never let a piece of art touch the glass directly. Moisture can condense on the glass like a terrarium causing foxing or even mold to grow at that spot. If a photograph (both antique and modern) gets wet, it can cause the image to stick to the glass making it impossible to remove. Frame molding must be strong enough and deep enough to support all the layers. An old frame will sometimes need to be modified to meet these criteria.

Reusing Old Frames

If an old frame is to be re-used it should be carefully cleaned and repaired, preserving all inscriptions and framing labels. The frame, mount and glass may be of historical significance. Old decorative mounts such as Victorian gilt mounts can sometimes be re-used with an internal lining. Eye hooks need to be secured and wire should be replaced.

Conservation Matting

The conservation mat comprises a window mat and backing board. To provide adequate physical and environmental protection both boards should be hinged along one edge using either a conservation gummed white paper tape or linen tape, (never pressure sensitive tapes).

Museum Mat Board

Because the picture is in direct contact with the mat, the choice of mat board is crucial to protecting it. Museum mat boards are usually solid core, made from 100% cotton rag - a traditional paper making material, proven stable over hundreds of years. It can be un-buffered (neutral pH) or buffered with an alkali deposit which prolongs the stability of the board and provides some extra protection.

French mat- a hand painted mat with a water color panel and water color lines. Hand painted to enhance the colors in the print or map

Fabric wrapped mat- hand wrapped in silk or linen usually has a bottom mat or liner so it doesn’t lay against the artwork.

Matting photographs - photographs are a special case because some types may be affected by alkalinity. Therefor they should not  come into contact with an alkaline buffered board. Solid rag mats are available in limited colors.

Gold leaf liner- Acid free board is cut to show a 1/4 border below the top mat. It is filed smooth and then gesso is applied in layers. Next is a layer of clay (red or yellow) and finally 22 kt gold leaf is applied.

Black Glass mat- not actually a mat. Black paint and/or gold leaf is applied to the back of a piece of museum glass or UF3 plexi. An unseen acid free liner is cut to space the glass from the actual piece of art.

Floating A piece of art can be floated or without a mat if there is a spacer or some kind of liner used in the construction of the frame. Sometimes it is pleasing to show the deckled edges of a document or print. In the case of fabric or a flag a conservator will carefully stitch the piece to a stable backing. When presenting a document or a print careful attention is used to place a couple of hidden hinges behind the piece and it just “hangs” free.


Restriction of movement can be detrimental. Hinges should allow the picture to hang safely; they should be applied to the top edge and adhered to the backing mat . Adhesives used must be easy to remove at a future date, and must neither stain nor darken with age. The ideal adhesive is freshly made wheat or rice starch paste. Conservators like to use Japanese paper hinges as they are thin pliable and strong. Pressure sensitive tapes, such as Scotch tape and masking tape have no place in conservation framing. They cause permanent damage to the picture by staining and become difficult or even impossible to remove. Water-soluble conservation gummed white paper mounting tape is acceptable but pressure sensitive archival conservation tapes are not recommended for use directly on the picture.

Glass or Glazing:

Works on paper need to be mounted clearly away from the glass to allow for air circulation and movement. Pastels and chalk drawings should be spaced from the glass, using either double or triple mounts or by using spacers (thin strips of plexi) tucked under the rabbet.

TruVue Conservation Clear Glass: Conservation Clear Glass transmits 91% of light to the artwork, but blocks more than 97% of the Ultraviolet light from reaching the artwork. By comparison, regular picture glass transmits 91% of the light to the artwork but blocks only 47% of the UV rays . While all glass has a barely green cast to it, Conservation Clear is slightly greener.

TruVue Conservation Reflection Control:This glass has the same UV protective properties as Conservation Clear, and it is also etched one one side. This etched surface diffuses light to reduce unwanted glare. There is a slight distortion of the image due to the surface being etched. Up to three mats can be used with this reflection control glass before the distortion caused by the etched surface becomes an issue. One of the problems I feel is that if glare from reflected light is an issue and the piece is of some value that it probably shouldn’t be hung in that spot. It is really the customers decision and the Customer is always right but not something I use at all.

Museum Glass: This is truly an extraordinary glass. It provides the same UV blocking protection of Conservation Clear and Conservation Reflection Control in that it blocks more than 97% of the Ultraviolet rays. In addition, Museum Glass has a very special antireflective surface far superior to a typical non-glare glass. A special coating is used in extremely thin layers to break up the incoming light rays so that they don't bounce back off the glass producing a glare. Because the rays don't bounce off, the picture is actually more illuminated than with clear glass. Clear glass transmits 91% of light to the artwork, while Museum Glass transmits more than 97% of light to the artwork.

UV Filtering Plexi glass (UF3) : Blocking 99% of the UV rays. When UF3 Plexi glass is viewed from the side it has a yellow cast to it though it doesn’t change the color of the image thru the glass. It has another advantage in that it is unbreakable. If the piece was to fall off the wall or be dropped the frame might break but the glass won’t shatter causing the print to get scratched. Another advantage is that the weight is much less than glass causing less strain on the frame and hanging supports. We use UV plexi on anything over 30 inches just because of weight issues unless specifically asked not to. I actually have it on alot of my pieces at home because of the Hurricane issue and the having to move the art during those threats. The only problem however is that plexi glass is easily scratched.

Never use Plexi glass on glaze pastels, chalks or charcoals. Because of static that can build up on plastics it can destroy or pull the image off the art’s surface.

Never use Windex or commercial cleaners because they can cause a film to coat the glass.... a special plexi cleaner is available but in most cases just clean water and soft cloths are all that is needed. Even paper towels will scratch the surface of this delicate "glass".

The matted picture, glass and backing can be sealed around the edges with gummed paper to prevent vermin or possible smoke damage. The backing board should be made of a stable, rigid material, such as pH neutral conservation backing board or acid free foam core.

Fittings for Hanging

All hanging fittings should be strong and secure. The tension of the cord or wire should be checked to ensure that there is no strain on the frame when it is hanging.

Screw-eyes, hanging plates or rings should be attached to the frame itself and must be of sufficient strength to carry the weight involved.
Use appropriate weight hanging nails. On larger pieces I usually use two hangers placed a distance apart. It is easier to level it and for it to stay that way.

Final Tips

Avoid hanging or storing anything in the basement, attic, or any other place with extremes in temperature and humidity. A stable, cool, dry environment is best.

Avoid hanging pieces on outside walls, but if you must, check frequently for signs of mold or dampness. Tip: slice a wine cork to about an 3/4 inch thickness and glue to the back on the bottom two corners of the frame, the piece because it is hung from a nail hangs away from the wall. In placing the spacers on the bottom it lets air circulate around the piece, helping keep it dry.

Avoid hanging objects in direct sunlight or any other intense light source. Control exposure to ultra violet light through glazing or placement away from a UV source. Occasionally rotate framed objects to cut down on the duration of light exposure.

Avoid hanging framed objects directly above working fire places or radiators.

Enjoy your art! Find a good framer and proudly hang your collections. Don't stick them under a bed where no one can see them.